Combustion properties of macerals from four Alberta coals

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Energy Sources

DOI:https://doi.org/10.1080/00908319508946110· OSTI ID:178335

Gentzis, T; Chambers, A ^[1]

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1. Alberta Research Council, Devon, Alberta (Canada). Coal and Hydrocarbon Processing Dept.

The combustibility of handpicked vitrinite (Vt) and inertinite (IN) concentrates from 4 Alberta coals ranging in rank from subbituminous C to low-volatile bituminous (LVB) was measured and compared with the parent coal. The combustion properties of the concentrates were studied by routine analysis of the maceral concentrates, examination of low-temperature reactivity on a thermogravimetric analyzer, examination of high-temperature burnout profiles on the entrained flow reactor, and measurement of char combustion reactivity on a single-particle combustor. The structure of partially combusted chars from two of the coals and their maceral concentrates were examined using SEM. Low-temperature oxidation of pyrolysis chars indicated that all of the samples had similar activation energies of between 29,900--35,600 cal/mol. For 3 of the coals, the IN char had lower reaction rates under these conditions. Under entrained flow combustion conditions at 1,000 C, the subbituminous and high-volatile bituminous (HVB) coals were very reactive, with 90% burnout in air in less than 0.2 s. The initial weight loss of the IN maceral during devolatilization was significantly less than the Vt maceral or parent coal for the three reactive coals. However, the chars formed from IN burned at similar rates to Vt char. The similarity in maceral char combustion rates was confirmed on a single-particle combustor; however, the three reactive coals and their macerals burned at the diffusion limit. Although char combustion rates were similar, the low initial weight loss of the IN fraction would result in longer combustion times for complete combustion of the IN char. SEM revealed that IN chars from the HVB and the LVB coals generally retained their original morphology during devolatilization, while the Vt macerals went through a plastic phase. The reactive HVB coal formed porous, spongelike chars, while the unreactive LVB coal developed vesicular chars with low surface area.

• Sponsoring Organization: USDOE
• OSTI ID: 178335
• Journal Information: Energy Sources, Journal Name: Energy Sources Journal Issue: 6 Vol. 17; ISSN 0090-8312; ISSN EGYSAO
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
ACTIVATION ENERGY
CHARS
COMBUSTION PROPERTIES
COMPARATIVE EVALUATIONS
MORPHOLOGY
SUBBITUMINOUS COAL
THERMAL GRAVIMETRIC ANALYSIS